Sanding pad assembly



May I, 1951 c. BURLEIGH SANDING PAD ASSEMBLY 3 Sheets-Sheet 1 Filed 001;. 12,' 1949 INVENTOR.

A. C. BURLEIGH SANDING PAD ASSEMBLY May 1, 1951 3 Sheets-Sheet 2 Filed Oct. 12, 1949 INVENTOR.

May 1, 1951 A. c. BURLEIGH SANDING PAD ASSEMBLY Filed Oct. 12, 1949 3 Sheets-Sheet 5 m w m m Patented May 1, 1951 UNITED STATES PATENT OFFICE This invention relates to a sanding pad assembly for a portable sanding machine such as is commonly used for sanding, polishing, burnishing, etc., metal surfaces.

Machines of this type are used quite generally in the automobile trade not only for providing the automobile body with a desirable surface finish, but also for removing surface blemishes. scratches, paint, etc., during a refinishing job on used cars.

For some refinishing work it is desirable to perform a regular sanding operation which involves the application to the sanding Dad by the operator of considerable pressure, while for other refinishing work, such for instance as a so-called feathering operation, it is important that the sanding pad should be operating against the metal surface under a relatively light pressure.

It is one of the objects of the present invention to provide a sanding pad assembly that is so constructed that it can be converted from one capable of performing a sanding operation under more or less heavy pressure to one designed to perform a so-called feathering operation, and vice versa, without removing the pad assembly from the machine or without removing and replacing any part of the pad assembly.

It is a further object of the invention to provide a sanding pad assembly with a control member with, upon manipulation by the operator, will convert the pad into one adapted either for a regular sanding operation, which requires the application of considerablepressure to the sanding pad, or for a feather edging operation, which requires the application of a relatively light pressure to the sanding pad.

A further object of the invention is to provide a sanding pad having a control member which in one position provides a relatively light friction drivin connection between the driving shaft on which the pad assembly is mounted and the pad element, which driving friction is sufficient for the feather edging operation, and in another position functions to lock the pad assembly to the driving shaft so that the pad will be positively driven by the driving shaft.

In order to give an understanding of the invention I have illustrated in the drawings a selected embodiment thereof which will now be described, after which the novel' features will be pointed out in the appended claims.

In the drawings,

Fig. 1 is a fragmentary view showing a portion of the head of a portable sandin machine with a pad assembly embodying my invention mounted on the driving shaft,

Fig. 2 is a top plan view of the pad assembly.

Fig. 3 is in enlarged section on the line '3-3, Fig. 1 showing the control member in a position to provide a friction drive between the driving shaft and the pad.

Fig. 4 is a similar view showing the control member in a position to provide a positive drive between the driving shaft and the pad.

Fig. 5 is an enlarged section on the line 5-5, Fig. 2. V

Fig. 6 is a fragmentary enlarged section on the line 6-6, Fig. 2.

Fig. '7 is a fragmentary sectional view on the line 3-3, Fig. 1 showing the driving and driven members in one relative position.

In the drawings l indicates the head of a portable sanding machine and 2 indicatesthe pad assembly. The head I is provided with a driving shaft 3 on which the pad assembly is mounted and which is driven by suitable gear ing from a motor (not shown) enclosed in the head I.

The pad assembly 2 is shown as having a hollow hub portion 4 which is interiorly screw threaded to receive the screw threaded end 5 of the driving shaft 3.

The pad assembly includes a backing member 6 to the face of which is adhesively united a pad I of felt, soft wool-pile, or some other suitable yielding material and which is faced with the sanding disk 8 as usual in pad assemblies.

The backing member 6, which may be of metal or of some rubber material, is secured to a supporting member 9 by means of attaching screws ID. The supporting member Bis provided with an axial projection II which is exteriorly screw threaded to receive a clamping nut l2 by which the sandpaper facing 8 is secured to the pad I. The backing member 6 is shown as having a central opening 13 through which the projection ll extends, and the clamping nut l2 extends through an opening in the pad 1 and the sandpaper facing 8 and is provided with a clamping flange M by which the central portion of the sandpaper is firmly clamped to the pad I, as usual in sanding machines.

My improved pad assembly comprises means providing a driving connection between the hub 4 which is mounted on the drivin shaft 3 and the backing member 6 and pad 1, which may be either in the form of a friction drive suitable for feather edging operation, or in the form of aposi tive drive suitable for regular sanding operation. I

My improved padassembly is also provided with a control member which can be manipulated by the operator to convert the driving connection between the hub 4 and the backing member 6 and pad i from a friction driving connection to a positive driving connection, or vice versa.

The hub 4 is formed with a flange portion i which occupies a recess 16 with which the supporting member 9 is provided. Secured to the supporting member by means of attaching screws I! is a retaining ring [8 having a. central opening [9 through which the hub 4 extends, the under face of said retaining ring being yieldably held in contact with the upper face 2| of the flange 5. The two faces 20 and ,2] provide between them a frictional driving connection between the hub 4 and the padassembly. hub 4 and flange ls constitute a, drivin member having the friction surface 21 and thesupporting member 9 and retaining ring l8 constitute -.a driven member having the friction surface 20.

It will be noted that .the friction surface. 2| of the drivingmember faces away from the pad element while :the friction surface 2!} of the driven'mem'ber faces toward the pad element.

The two friction surfaces 28 and .21 are normally yieldingly held in engagement with each other through the medium of a spring 22 which is located in a spring-receiving recess or chamthe follower 24 having a rounded end which rests in a recess 25 with which the flanged portion of the hub 4 is provided. Said follower 24 is shown as having a stem 26 which extends into the coil spring '22 and which thereby serves to retain the follower 24 in proper position.

The spring 22, therefore, acts to apply a force against the driving member '4, E5, in an upward direction Fig. 5, and against the driven member l8, in a downward direction, thereby normally to hold the friction surfaces 20 and 2! yieldingly in frictional engagement.

The tension of the spring 22 is such as to pro vide the proper frictional engagement between the frictional surfaces 29 and 21 for normal feather edging operation.

The recess H5 in the driven member is slightly deeper than the thickness of the flange l5, thereby providing a slight clearance 2'! between said flange and the bottom of the recess. If excessive pressure is applied "to the pad during a finishing operation, the clearance 2? permits a slight compression of the spring 22 thereby reducing the frictional engagement between the friction faces 20 and 21 to such an extent that the pad assembly may be stalled.

As stated above my invention includes means under the control of the operator by which the driving connection between the hub 4 and the backing member I; and pad I can be converted from the friction drive above referred to to a positive drive and can also be converted from the positive drive back to the friction drive. For this purpose the supporting member 9 is provided with a recess :28 in which is received a looking pawl 2e that is pivotally mounted intermediate of its ends on a pivot pin anchored in the supportin member 9. Said pawl 29 is adapted to turn on its pivot into either an inoperative position shown in Fig. 3 or an operative positin shown in Fig. 4.

The flange l5 of the hub 4 is provided in its periphery with a notch '3! adapted to receive the The nose 32 of the pawl when the latter is in its operative position as shown in Fig. 4. When the parts are in the position shown in Fig. 4, the flange i5 of the hub 4 will be positively locked to the supporting member 8 and thus to the backing member 5 and pad I, it being understood that when the machine is in operation the hub 4 is rotating in the direction of the arrow in Fig. 4.

When, however, the locking pawl is in its in operative position shown in Fig. 3, then the driving torque between the flange l5 and supporting member ,9 is only that due to the frictional engagement between the friction faces 20 and 2|.

The pad assembly is provided with a control member by wLich the pawl 29 can be moved into either its operative or its inoperative position. This control member is in the form of a ring 33 which encircles the supporting member 9 and is provided with a spring pressed pin 34 that bears against the outer face of the pawl 29. This pin '34 is backed by a spring 35 which is confined in a spring-receiving recess 36 with which the control member 3315 provided.

The control member 33 is capable .of a slight turning movement on the supporting member .9, and when said control member is in the position shown in Fig. 3, the pin 34 is engaging the rear end 31 of the pawl and the tension of the spring 35 will swing the pawl into ,its inoperative posltion with its nose 32 outside the peripheral line of the flange 15.

When, however, the control member 33 isturned into the position shown in Fig. 4, the pinwill bear against the nose end of the pawl and the spring will exert a pressure against said nose end tending to turn it inwardly into a po-' sition to engage the notch 31, thereby locking the supporting member .9, and consequently thebacking member 6 and pad I, to the hub 4 and thus providing a positive driving connection be-- tween the driving shaft and the pad.

If it be assumed that the control member 33 is adjusted to maintain the locking pawl 2.! inits inoperative position shown in Fig. 3, there-- by converting the pad assembly into one adapted for a feather edging operation, and it is desired to convert the pad assembly into one for per-- forming a sandin operation, the control member 33 will be turned. from the position shown in Fig. 3 to that shown in Fig. 4, and this may be accomplished regardless of the relative positions of the flange l5 and the supportng member 9, that is, regardless of the relative positions of the notch 3i and the pawl 2-9.

If at the time the control member is operated to convert the pad assembly from one in which the pad is frictionally driven through the frictional engagement of the surfaces 2| and 22, to a pad assembly in which the pad is positively driven, the notch 3! is out of register with the pawl 29 as shown in Fig. '7, the turning move-- ment of the control member will move the pin over the outer face of the pawl thereby compressing the spring 35. If, with the parts in this position, the pad is pressed against the work. with sufficient force to cause a slippage between the friction faces 2!, 22, the turning movement, of the hub 4 and flange [5, relative to the -sup porting member 9 andthe pawl 29 carried thereby, will bring the notch "3| into register with the nose end of the pawl, at which time the spring 3-5 will force the pawl nose into the notch thereby providing a positive driving connection for the sanding operation.

The turnin movement of the control member 33 islimited in one direction by the engagement of the spring-pressed pin 34 with the end wall 39 of the recess 28, and the turning movement of said control member in the other direction is limited by the engagement of the pin 3 with a stop pin 38 which is mounted in the supporting member 9 and is located within the recess 28. The nose end 32 of the pawl 29 is provided with a recess 40 in which the stop pin 38 is received when the pawl is in its inoperative position.

The control member may conveniently be provided with some indication marks to indicate to ;the operator the direction in which it should be turned to provide either the frictional or the positive driving connection between the hub and the supporting member 9. In the drawings the control member isshown as provided with a let- ,ter Sfland an accompanying arrow t indicate chine comprising a driving member having a friction surface, a pad element, a driven member cooperatin with the driving member and also having a friction surface, spring means normally maintaining said friction surfaces in frictional engagement thereby to establish a frictional driving connection between thedriving member and the pad element, a pawl associated with the pad element and means to lock said pawl to the driving member thereby to establish a positive driving connection between the driving member and the pad element.

2. A sanding pad assembly for a sanding machine comprising a driving member having a friction surface, a pad element, a driven member connected with the pad element and also having a friction surface cooperatin with that of the driving member, spring means normally maintaining said friction surfaces in frictional engagement thereby to establish a frictional driving connection between the driving member and the pad element, a pawl associated with the pad element, a movable control member, and means operative when the control member is in one position to hold the pawl in an inoperative position out of engagement with the driving member and when the control member is in another position to hold the pawl in an operative position in engagement with the driving member, thereby converting the frictional driving connection into a positive driving connection.

3. A sanding pad assembly for a sanding machine comprising a driving member having a able control member, and-means operative when the control member is in one position to hold the pawl in an inoperative position out of engagement with the driving member and. when the control member is in another position to hold the pawl in an operative position in engagement with the notch in the driving member, thereby conprising a driving member having provision for attachment to the driving shaft of a sanding surface, a pad element, a driven member consurface cooperating with that ofthe driving member, and spring means normally maintaining said friction surfaces in frictional engagement, thereby. to establish a frictional driving connection between the driving member and the pad element.

5. A portable sanding machine comprising'a head, a drivin shaft mounted therein, a driving member connected to said shaft and having a friction surface, a driven member having a friction surface'cooperating with that of the driving member, a pad element secured to the driven member, the friction surface of the driving member facing away from the pad element and that of the driven member facing toward the pad element, and a spring acting on the driving member and normally holdin the friction surfaces yieldingly in frictional engagement.

6. A portable sanding machine comprising a head, a driving shaft mounted therein, a driving member connected to said shaft and having a friction surface, a driven member having a friction surface cooperating with that of the driving member, a pad element secured to the driven member, the friction surface of the driving member facing away from the pad element and that of the driven member facing toward the pad element, and spring means acting against both the driving member and the driven member and normally holding the friction surfaces yieldingly in frictional engagement.

7. A sanding machine comprising a head, a

driving shaft mounted therein, a driving member connected to said shaft and having a friction surface, a driven member having a friction surface cooperating with that of the driving member and also having a spring-receiving chamber, a pad element secured to the driven member, the friction surfac of the driving member facing away from the pad element and that of the driven element facing toward the pad element and a spring in said spring-receiving chamber acting against both the driving and driven members and normally holding said friction surfaces yieldingly in frictional engagement.

8. A portable sanding machine comprising a head provided with a driving shaft, a driving member mounted on said shaft and having a friction surface, a driven member presenting a friction surface cooperating with that of the driving member, a pad element secured to the driven member to rotate therewith, and spring means normally maintaining said friction surfaces in pre-determined frictional engagement regardless of the speed of rotation of the driving member.

9. A sanding pad assembly for a sanding ma- 3 chine comprising a driving member having a friction surface, a driven member having a friction surface cooperating with that of the driving member, a pad element secured to the driven member, spring means normally maintaining aid friction surfaces "in frictional engagement thereby to "establish a frictional driving'connectionbetween the driving member and the driven member, a pawl associated with'the pad element and movable from an inoperative 'position'into an operative ,position'in which it positively couples the driven member toth'e driving member, and means carried by therdrivenzmember'to move'the pawl from one position to the other. 7

10. A sanding pad assembly for a sanding machine comprising a driving member having a frictionsurface, a driven member having a friction surface cooperating with that of the driving member, spring means "normally maintainingsaid friction surfaces in "frictional engagement, a pad element connected to the driven member, an an- ;nular control member associated with the pad element and situated coaxial thereof, said control "member being turnable about its axis into either one of two'posit'ions, and means controlled by the control memberfor positively coupling the driving member to the driven member when said control member is in one position and for releasing said positive coupling when the control member is in the other position.

ARTHUR C. BURLEIGH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,445,676 Furber' Feb. 20, 1923 2,122j892 Orr July 5, 1938 2,260,644 Siebert et a1 Oct. 28, 1941 2,359,608 Baur Oct. 3, 1944 360,489 Gillett Oct. 17, 1944 2,371,021 Berry Mar. 6, 1945 2,454,726 Tott Nov. 23, 1948 2,501,554 Watson Mar. 21, 1950 

